DESCRIPTION: The overall goal of the proposed experiments is to understand the cis-acting elements through which switch recombination is regulated. The investigator has established a transgenic mouse model that measures properly regulated germline transcription from the murine g1 gene. He has also prepared a line of transgenic mice that can undergo switch recombination to g1. He will investigate the function of the cis-acting elements in the g1 gene by further localization of the elements in transgenes, by analysis of their ability to interact with other promoters, by their deletion from the endogenous g1 gene and by studying the effect of mutations of the cis-acting elements on both germline transcription and switch recombination. He will also study the transcriptional regulation of the g2a gene, emphasizing both cis-acting elements in the g2a gene and in the heavy chain 3 regulatory region.